A variety of different products are transported in shipping containers. Products are packed into the container by a shipper, and then the container doors are closed and secured with some type of lock. The locked container is then transported to a destination, where a recipient removes the lock and unloads the container.
It is often advantageous to the shipper if some form of monitoring can be carried out while the container is being transported. As one example, the cargo in the container may be relatively valuable products such as computers or other electronic devices, and thieves may attempt to break into the container and steal these products while the container is in transport. As a different example, the cargo in the container may include products such as fresh fruit, for which it is advantageous to continuously monitor temperature, humidity and/or other environmental conditions, in order to avoid or minimize spoilage. Another consideration is that it may be beneficial to the shipper and/or the recipient to be able to accurately track the current location of the container as it travels from the shipper to the recipient.
It is not cost-feasible to have a person watch a container at all times in order to provide security and/or monitoring. Accordingly, electronic systems have previously been developed to provide a degree of automated security and/or monitoring. For example, one existing approach is to attach a radio frequency identification (RFID) tag to a container. The tag then provides monitoring as to both security and environmental conditions, and can send wireless signals that contain status information, including warnings about alarm conditions. Although pre-existing systems of this type have been generally adequate for their intended purposes, they have not been satisfactory in all respects. By way of example and not limitation, one drawback is that, throughout most of the journey of the container, the RFID tag is outside the range of communication with any RFID system, and thus is not able to reliably communicate information to a system or a person at a remote location. In many locations where an RFID system would be useful, no RFID system is installed. Also, even when the tag is within the communication range of an RFID system, that RFID system may be owned or operated by someone other than the shipper or the recipient for the container of interest. Consequently, the tag on the container may be denied any use of that system, or there may be unreasonable costs, delays and/or challenges involved with an attempt by the tag to actually communicate information through that RFID system.